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25 // 25 //
>> 26 // $Id$
26 // 27 //
27 // ------------------------------------------- 28 // -------------------------------------------------------------------
28 // 29 //
29 // GEANT4 Class header file 30 // GEANT4 Class header file
30 // 31 //
31 // 32 //
32 // File name: G4BetheHeitlerModel 33 // File name: G4BetheHeitlerModel
33 // 34 //
34 // Author: Vladimir Ivanchenko on base 35 // Author: Vladimir Ivanchenko on base of Michel Maire code
35 // 36 //
36 // Creation date: 19.04.2005 37 // Creation date: 19.04.2005
37 // 38 //
38 // Modifications by Vladimir Ivanchenko, Miche << 39 // Modifications:
>> 40 // 02-02-06 Remove InitialiseCrossSectionPerAtom();
39 // 41 //
40 // Class Description: 42 // Class Description:
41 // 43 //
42 // Implementation of gamma conversion to e+e- << 44 // Implementation of gamma convertion to e+e- in the field of a nucleus
43 // For details see Physics Reference Manual << 45 //
44 46
45 // ------------------------------------------- 47 // -------------------------------------------------------------------
46 // 48 //
47 49
48 #ifndef G4BetheHeitlerModel_h 50 #ifndef G4BetheHeitlerModel_h
49 #define G4BetheHeitlerModel_h 1 51 #define G4BetheHeitlerModel_h 1
50 52
51 #include "G4VEmModel.hh" 53 #include "G4VEmModel.hh"
52 #include "G4PhysicsTable.hh" 54 #include "G4PhysicsTable.hh"
53 #include "G4Log.hh" <<
54 <<
55 #include <vector> <<
56 55
57 class G4ParticleChangeForGamma; 56 class G4ParticleChangeForGamma;
58 class G4Pow; <<
59 class G4EmElementXS; <<
60 57
61 class G4BetheHeitlerModel : public G4VEmModel 58 class G4BetheHeitlerModel : public G4VEmModel
62 { 59 {
63 60
64 public: 61 public:
65 62
66 explicit G4BetheHeitlerModel(const G4Particl << 63 G4BetheHeitlerModel(const G4ParticleDefinition* p = 0,
67 const G4String& << 64 const G4String& nam = "BetheHeitler");
68 65
69 ~G4BetheHeitlerModel() override; << 66 virtual ~G4BetheHeitlerModel();
70 <<
71 void Initialise(const G4ParticleDefinition*, <<
72 67
73 void InitialiseLocal(const G4ParticleDefinit << 68 virtual void Initialise(const G4ParticleDefinition*, const G4DataVector&);
74 G4VEmModel* masterModel) override; <<
75 69
76 G4double ComputeCrossSectionPerAtom(const G4 << 70 virtual G4double ComputeCrossSectionPerAtom(
77 G4double kinEnergy, << 71 const G4ParticleDefinition*,
78 G4double Z, << 72 G4double kinEnergy,
79 G4double A=0., << 73 G4double Z,
80 G4double cut=0., << 74 G4double A=0.,
81 G4double emax=DBL_MAX) override; << 75 G4double cut=0.,
82 << 76 G4double emax=DBL_MAX);
83 void SampleSecondaries(std::vector<G4Dynamic <<
84 const G4MaterialCutsCouple*, <<
85 const G4DynamicParticle*, <<
86 G4double tmin, <<
87 G4double maxEnergy) override; <<
88 77
89 // hide assignment operator << 78 virtual void SampleSecondaries(std::vector<G4DynamicParticle*>*,
90 G4BetheHeitlerModel & operator=(const G4Beth << 79 const G4MaterialCutsCouple*,
91 G4BetheHeitlerModel(const G4BetheHeitlerMod << 80 const G4DynamicParticle*,
>> 81 G4double tmin,
>> 82 G4double maxEnergy);
92 83
93 protected: << 84 private:
94 85
95 inline G4double ScreenFunction1(const G4doub << 86 G4double ScreenFunction1(G4double ScreenVariable);
96 87
97 inline G4double ScreenFunction2(const G4doub << 88 G4double ScreenFunction2(G4double ScreenVariable);
98 89
99 inline void ScreenFunction12(const G4double << 90 // hide assignment operator
>> 91 G4BetheHeitlerModel & operator=(const G4BetheHeitlerModel &right);
>> 92 G4BetheHeitlerModel(const G4BetheHeitlerModel&);
100 93
101 void InitialiseElementData(); << 94 G4ParticleDefinition* theGamma;
102 << 95 G4ParticleDefinition* theElectron;
103 struct ElementData { << 96 G4ParticleDefinition* thePositron;
104 G4double fDeltaMaxLow; << 97 G4ParticleChangeForGamma* fParticleChange;
105 G4double fDeltaMaxHigh; << 98 };
106 }; <<
107 <<
108 static const G4int gMaxZet; <<
109 <<
110 G4Pow* fG4Calc; <<
111 const G4ParticleDefinition* fTheGamma; <<
112 const G4ParticleDefinition* fTheElectr <<
113 const G4ParticleDefinition* fThePositr <<
114 G4ParticleChangeForGamma* fParticleC <<
115 G4EmElementXS* fXSection{ <<
116 99
117 G4bool isFirstInstance{false}; << 100 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
118 G4bool useEPICS2017{false}; <<
119 101
120 static std::vector<ElementData*> gElementDa << 102 inline G4double G4BetheHeitlerModel::ScreenFunction1(G4double ScreenVariable)
121 }; <<
122 103
123 // << 104 // compute the value of the screening function 3*PHI1 - PHI2
124 // Bethe screening functions for the elastic ( <<
125 // Bethe's phi1, phi2 coherent screening funct <<
126 // by using (the universal) atomic form factor <<
127 // Fermi model of the atom (using numerical so <<
128 // screening function instead of Moliere's ana <<
129 // numerical results can be well approximated <<
130 // especially near the delta=1 limit) by: <<
131 // ## if delta <= 1.4 <<
132 // phi1(delta) = 20.806 - delta*(3.190 - 0.57 <<
133 // phi2(delta) = 20.234 - delta*(2.126 - 0.09 <<
134 // ## if delta > 1.4 <<
135 // phi1(delta) = phi2(delta) = 21.0190 - 4.14 <<
136 // with delta = 136mc^2kZ^{-1/3}/[E(Eg-E)] = 1 <<
137 // Eg is the initial photon energy, E is the t <<
138 // the e-/e+ pair, eps0 = mc^2/Eg and eps = E/ <<
139 105
140 // Compute the value of the screening function <<
141 inline G4double G4BetheHeitlerModel::ScreenFun <<
142 { 106 {
143 return (delta > 1.4) ? 42.038 - 8.29*G4Log(d << 107 G4double screenVal;
144 : 42.184 - delta*(7.444 <<
145 } <<
146 108
147 // Compute the value of the screening function << 109 if (ScreenVariable > 1.)
148 inline G4double G4BetheHeitlerModel::ScreenFun << 110 screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
149 { << 111 else
150 return (delta > 1.4) ? 42.038 - 8.29*G4Log(d << 112 screenVal = 42.392 - ScreenVariable*(7.796 - 1.961*ScreenVariable);
151 : 41.326 - delta*(5.848 << 113
>> 114 return screenVal;
152 } 115 }
153 116
154 // Same as ScreenFunction1 and ScreenFunction2 << 117 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
155 inline void G4BetheHeitlerModel::ScreenFunctio << 118
156 << 119 inline G4double G4BetheHeitlerModel::ScreenFunction2(G4double ScreenVariable)
>> 120
>> 121 // compute the value of the screening function 1.5*PHI1 - 0.5*PHI2
>> 122
157 { 123 {
158 if (delta > 1.4) { << 124 G4double screenVal;
159 f1 = 42.038 - 8.29*G4Log(delta + 0.958); << 125
160 f2 = f1; << 126 if (ScreenVariable > 1.)
161 } else { << 127 screenVal = 42.24 - 8.368*std::log(ScreenVariable+0.952);
162 f1 = 42.184 - delta*(7.444 - 1.623*delta); << 128 else
163 f2 = 41.326 - delta*(5.848 - 0.902*delta); << 129 screenVal = 41.405 - ScreenVariable*(5.828 - 0.8945*ScreenVariable);
164 } << 130
>> 131 return screenVal;
165 } 132 }
>> 133
>> 134 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
166 135
167 #endif 136 #endif
168 137